Problem: $\dfrac{2}{3} + \dfrac{3}{10} = {?}$
Explanation: $ = {\dfrac{2 \times 10}{3 \times 10}} + {\dfrac{3 \times 3}{10 \times 3}} $ $ = {\dfrac{20}{30}} + {\dfrac{9}{30}} $ $ = \dfrac{{20} + {9}}{30} $ $ = \dfrac{29}{30}$